1. Child Health Evaluation and Research (CHEAR) Unit,
2. Division of General Pediatrics, Department of Pediatrics and Communicable Diseases, and
3. Department of Health Management and Policy, School of Public Health, University of Michigan, Ann Arbor, Michigan;
4. American Board of Pediatrics, Chapel Hill, North Carolina; and
5. Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California